JP6129639B2 - Magnetic resonance imaging system - Google Patents

Description

  Embodiments described herein relate generally to a magnetic resonance imaging apparatus.

  Magnetic resonance imaging is based on magnetic resonance signal data generated by exciting the nuclear spin of a subject placed in a static magnetic field magnetically with an RF (Radio Frequency) pulse of the Larmor frequency. This is a photographing method for generating an image. This magnetic resonance imaging is performed by a magnetic resonance imaging apparatus (hereinafter referred to as “MRI (Magnetic Resonance Imaging) apparatus” as appropriate).

  Conventionally, MRI apparatuses are distributed and installed in an imaging room, a machine room, an operation room, or the like according to the type of component. The wall surface of the imaging room is shielded, and a frame including a static magnetic field magnet, a gradient magnetic field coil, an RF (Radio Frequency) transmission coil, and a bed is installed in this imaging room. On the other hand, other components are installed in the machine room and the operation room. For example, several components such as a gradient magnetic field power supply unit, a gradient magnetic field amplifier unit, an RF transmission unit, and an RF transmission amplifier unit are installed in the machine room. However, depending on the installation environment of the MRI apparatus, a sufficient space such as a machine room may not be secured.

Special table 2012-507329 gazette

  The problem to be solved by the present invention is to provide a magnetic resonance imaging apparatus capable of realizing space saving.

  The magnetic resonance imaging apparatus according to the embodiment includes an installation unit on which the electronic device can be installed. In addition, the magnetic resonance imaging apparatus according to the embodiment includes a drawing mechanism that pulls out the electronic device installed in the installation unit to a position away from the gantry by a predetermined distance under excitation of a static magnetic field magnet.

FIG. 1 is a functional block diagram showing the configuration of the MRI apparatus according to the first embodiment. FIG. 2 is a diagram for explaining a storage case according to the first embodiment. FIG. 3 is a view for explaining a drawing mechanism in the first embodiment. FIG. 4 is a view for explaining a drawing mechanism in the second embodiment.

  Hereinafter, an MRI apparatus according to an embodiment will be described with reference to the drawings. Note that the embodiments are not limited to the following embodiments. The contents described in each embodiment can be applied in the same manner to other embodiments in principle.

(First embodiment)
FIG. 1 is a functional block diagram showing the configuration of the MRI apparatus 100 according to the first embodiment. As shown in FIG. 1, the MRI apparatus 100 includes a static magnetic field magnet 101, a gradient magnetic field coil 102, a gradient magnetic field power supply unit 103, a gradient magnetic field amplifier unit 104, an RF transmission coil 105, an RF transmission unit 106, An RF transmission amplifier unit 107, an RF reception coil 108, and an RF reception unit 109 are provided. The MRI apparatus 100 includes a bed 111, a raw data collection unit 112, an image reconstruction unit 113, a real-time sequencer 120, a real-time manager 130, and a computer 135. In the following, as shown in FIG. 1, among the components of the MRI apparatus 100, a casing including the static magnetic field magnet 101, the gradient magnetic field coil 102, and the RF transmission unit 106 is referred to as a gantry 110. Further, the MRI apparatus 100 does not include the subject P (for example, a human body). Moreover, the structure shown in FIG. 1 is only an example. Each unit may be appropriately integrated or separated.

  The static magnetic field magnet 101 is a magnet formed in a hollow cylindrical shape, and generates a static magnetic field in a space inside the cylinder. The static magnetic field magnet 101 is, for example, a superconducting magnet or the like, and is excited by receiving a current supplied from a static magnetic field power supply unit (not shown). The static magnetic field magnet 101 may be a permanent magnet. In this case, the MRI apparatus 100 may not include a static magnetic field power supply unit. The static magnetic field power supply unit may be provided separately from the MRI apparatus 100.

  The gradient magnetic field coil 102 is a coil disposed inside the static magnetic field magnet 101 and formed in a hollow cylindrical shape. The gradient coil 102 receives a current from the gradient amplifier unit 104 and generates a gradient magnetic field. The gradient magnetic field power supply unit 103 generates a current to be supplied to the gradient coil 102 in accordance with a control signal from the real time sequencer 120. The gradient magnetic field amplifier unit 104 amplifies the current generated by the gradient magnetic field power supply unit 103 and supplies the amplified current to the gradient magnetic field coil 102.

  The RF transmission coil 105 is disposed inside the gradient magnetic field coil 102 and receives a supply of RF pulses from the RF transmission amplifier unit 107 to generate a high-frequency magnetic field. The RF transmission unit 106 generates an RF pulse to be supplied to the RF transmission coil 105 according to a control signal from the real-time sequencer 120. The RF transmission amplifier unit 107 amplifies the RF pulse generated by the RF transmission unit 106 and supplies it to the RF transmission coil 105.

  The RF receiving coil 108 receives a magnetic resonance signal (hereinafter referred to as “MR (Magnetic Resonance) signal”) generated from the subject P due to the influence of the high-frequency magnetic field, and outputs the received MR signal to the RF receiving unit 109.

  Note that the above-described combination of the RF transmission coil 105 and the RF reception coil 108 is merely an example. The RF coil may be configured by combining one or more of a coil having only a transmission function, a coil having only a reception function, or a coil having a transmission / reception function.

  The RF receiving unit 109 detects the MR signal output from the RF receiving coil 108 and generates MR data (hereinafter referred to as “raw data” as appropriate) based on the detected MR signal. Specifically, the RF receiving unit 109 generates raw data by digitally converting the MR signal output from the RF receiving coil 108. The RF reception unit 109 transmits the generated raw data to the raw data collection unit 112. For example, the RF receiving unit 109 is mounted inside the bed 111.

  The bed 111 includes a top plate 111a on which the subject P is placed. Normally, the bed 111 is installed so that the central axis of the cylinder of the static magnetic field magnet 101 is parallel to the longitudinal direction. The top plate 111a is movable in the longitudinal direction and the vertical direction, and is inserted into a space inside the cylinder inside the RF transmission coil 105 with the subject P placed thereon.

  The raw data collection unit 112 performs correction processes such as an averaging process, a phase correction process, and a rearrangement process on the raw data transmitted from the RF receiving unit 109, and the corrected raw data is converted into an image reconstruction unit 113. Send to. The image reconstruction unit 113 performs image processing such as Fourier transform and image filter on the raw data transmitted from the raw data collection unit 112 to reconstruct and reconstruct two-dimensional or three-dimensional image data. The image data is transmitted to the computer 135.

  The real-time sequencer 120 performs imaging of the subject P by driving the gradient magnetic field power supply unit 103, the RF transmission unit 106, and the RF reception unit 109 based on the data string transmitted from the real-time manager 130. The real-time manager 130 analyzes the shooting conditions transmitted from the computer 135 and generates a data string necessary for the operation of the real-time sequencer 120. In this data string, the intensity of the current supplied to the gradient magnetic field coil 102, the timing of supplying the current, the intensity of the RF pulse supplied to the RF transmitting coil 105, the timing of applying the RF pulse, the timing of detecting the MR signal, etc. Defined.

  The above-described units, the real-time sequencer 120, the real-time manager 130, and the like are all electronic devices, and are integrated circuits such as ASIC (Application Specific Integrated Circuit) and FPGA (Field Programmable Gate Array), CPU (Central Processing Unit). ), And an electronic circuit such as an MPU (Micro Processing Unit).

  The computer 135 performs overall control of the MRI apparatus 100. For example, the computer 135 includes a control unit, a storage unit, an input unit, and a display unit. The control unit is an integrated circuit such as an ASIC or FPGA, or an electronic circuit such as a CPU or MPU. The storage unit is a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. The input unit is a pointing device such as a mouse or a trackball, or an input device such as a keyboard. The display unit is a display device such as a liquid crystal display.

  Here, in the first embodiment, as shown in FIG. 1, the gradient magnetic field amplifier unit 104, the RF transmission amplifier unit 107, the raw data collection unit 112, and the image reconstruction unit 113 are installed in the photographing room. Specifically, these units are installed in an installation part (hereinafter referred to as “storage case”) provided on the side surface of the gantry 110.

  FIG. 2 is a view for explaining the storage case in the first embodiment. 2A is a perspective view of the storage case, and FIG. 2B is a cross-sectional view seen from the direction of the white arrow shown in FIG. As shown in FIG. 2, the storage case in the first embodiment has a double structure of a magnetic shield case 140 for shielding a magnetic field and an RF shield case 150 for shielding high-frequency electromagnetic waves. That is, each unit is first accommodated in the RF shield case 150. The RF shield case 150 is housed in the magnetic shield case 140.

  The magnetic shield case 140 mainly serves to protect the circuit of each unit housed in the magnetic shield case 140 by shielding the influence of a strong magnetic field generated in the gantry 110. On the other hand, the RF shield case 150 mainly prevents electromagnetic waves from the circuit of each unit housed in the RF shield case 150 from propagating as noise to the gantry 110 side, or conversely, the gantry 110. It serves to prevent electromagnetic waves from the side from propagating as noise to the circuit of each unit.

  In the first embodiment, the magnetic shield case 140 has a structure in which the side surface opposite to the side surface on the gantry 110 side is opened as shown in FIG. Thus, the magnetic shield case 140 can have a structure in which one surface is opened. On the other hand, the RF shield case 150 has a sealed structure as shown in FIG. The RF shield case 150 has a hermetically sealed structure, so that the internal operation clock noise is not leaked to the outside and does not affect the imaging, and the influence of the RF pulse and gradient magnetic field pulse from the system during the imaging is not affected. It achieves the duality of receiving and not malfunctioning. In addition, the difference between the magnetic shield case 140 and the RF shield case 150 is in the material in addition to the structure described above. A special material for shielding the influence of a strong magnetic field is used for the magnetic shield case 140. For example, a directional electrical steel sheet, non-oriented electrical steel sheet, permalloy, soft magnetic steel sheet, amorphous, or a microcrystalline magnetic material obtained by crystallizing a liquid quenching ribbon is used.

  By the way, each of the above-described units has a structure covered with metal and is often a heavy object. Therefore, when each unit is stored in the storage case shown in FIG. 2 and installed on the side surface of the gantry 110, for example, when these units are to be taken out of the storage case for the purpose of adjustment or parts replacement, There is a risk of being attracted to the gantry 110 by a strong force due to the attractive force of the magnetic field. As one method for avoiding such a situation, it is conceivable to perform operations such as adjustment and replacement of parts after demagnetizing the static magnetic field magnet 101. However, this demagnetization takes a long time and consumes helium gas, which is disadvantageous.

  Therefore, in the first embodiment, a mechanism capable of handling these units in an energized environment without demagnetizing the static magnetic field magnet 101 in the case of adjustment or replacement of parts is proposed. . Specifically, in the first embodiment, a mechanism is provided that allows only the RF shield case 150 from the storage case to be safely and simply pulled out from the gantry 110 to a certain distance. In this case, operations such as adjustment and component replacement are performed at a position away from the gantry 110 by a certain distance.

  FIG. 3 is a view for explaining a drawing mechanism in the first embodiment. FIG. 3A shows a state in which the RF shield case 150 is housed in the magnetic shield case 140 installed on the side surface of the gantry 110. For convenience of explanation, FIG. 3 shows a state in which the RF shield case 150 slightly protrudes from the magnetic shield case 140, but the embodiment is not limited to this and is completely within the magnetic shield case 140. May be. (B) shows a state in which the RF shield case 150 is pulled out from the magnetic shield case 140. Moreover, (C) is the figure which looked at the state of (B) from the mount frame 110. FIG. FIG. 3 shows a state in which the RF shield case 150 is pulled out while the cables 155 of each unit in the RF shield case 150 are connected to each unit.

  Here, the “constant distance from the gantry 110” is a distance at which the attractive force of the magnetic field is sufficiently reduced in operations such as adjustment and replacement of parts, for example, a 5 Gauss line shown in (B), It is the distance to 10 gauss lines. Since this distance can be calculated at the time of designing the static magnetic field magnet 101 or the like, the extraction mechanism is designed so that safe and simple extraction can be performed at least up to this distance.

  Further, the “safe drawer” is not a mechanism that is easily pulled by the suction force from the gantry 110 side while being pulled out to a certain distance, but has a certain hardness that resists this suction force. That is. This “hardness” may simply be a hardness in the sense that a certain amount of force is required to move, or this “hardness” is limited to movement in the magnetic field attraction direction. You may implement | achieve with the locking mechanism to apply. In addition, “simple drawer” means that, for example, a drawer or a return operation to the storage case can be performed only by a manual operation such as turning the handle with a light force.

  In order to realize such a safe and simple pull-out mechanism, in the first embodiment, a telescopic mechanism 160 as shown in FIG. 3B is proposed. For example, the expansion / contraction mechanism 160 is formed by rotating the rectangular plate-like components so that they can be overlapped at each end and closed or opened at an arbitrary angle. The expansion and contraction mechanism 160 becomes a mechanism that can be stretched and contracted by alternately connecting the number of components according to the distance. A similar structure may be referred to as a magic hand structure, an expanded structure, or the like.

  In the first embodiment, the joint between the parts is designed to have a certain hardness against the suction force. For example, the direction of drawing out from the gantry 110 is extended with a relatively small force, but the direction of storage in the storage case is determined according to the direction of rotation so as not to contract unless the force is relatively large. You may make it the structure where the force to be produced differs.

  Further, for example, when the parts are opened to a certain angle, a lock mechanism that is temporarily fixed at that angle may be used so that the parts are not further stretched or contracted. For example, when the angle of two parts reaches a certain angle in the expansion / contraction mechanism 160, the two parts are fixed at the angle and do not easily return to the storage direction. When the RF shield case 150 is subsequently pulled out, the angle between the next parts that have been folded gradually opens, and when the angle reaches again, the two parts are fixed at that angle, and the storage direction Not easy to return to. Thus, it becomes possible to pull out safely by setting it as the structure fixed in steps.

  In addition, regarding “a certain distance from the gantry 110”, for example, even if a mark is attached to the floor surface in the photographing room and the user looks at it and pulls out the RF shield case 150 to that position, for example. Good. Or, a structure that allows the user to recognize that it has reached a certain position when it is stretched to a safe distance (for example, it becomes impossible to stretch with a “click” sound). May be. On the other hand, when the RF shield case 150 is stored in the magnetic shield case 140, for example, a structure that allows movement in the storage direction by releasing the lock mechanism may be used.

  In the first embodiment, when the RF shield case 150 pulled out from the magnetic shield case 140 is stored in the magnetic shield case 140 again, the RF shield case 150 returns to the same position as before the drawer. Provide structure. For example, the structure may be such that the user can recognize that it is stored in a fixed position (for example, the user cannot move with a “click” sound). Further, for example, the RF shield case 150 may be fixed to the magnetic shield case 140 with pins or screws.

  By returning to the original position with high reproducibility in this way, the state of the magnetic field can be kept the same before and after the extraction. In other words, the magnetic field that has been uniformly maintained at the position before extraction can be similarly maintained even after each unit is extracted and returned.

  Further, for the purpose of preventing vibration from the gantry 110 from being transmitted during photographing, the RF shield case 150 is fixed to the magnetic shield case 140 fixed to the gantry 110 with pins or screws. May be. In addition, the structure which prevents each unit from transmission of a vibration is not restricted to this. For example, each unit may be fixed with pins or screws in the RF shield case 150. Further, for example, a shock absorbing material may be provided between the gantry 110 and the magnetic shield case 140 to make it difficult to transmit vibration on the gantry 110 side. Further, these methods may be appropriately selected or combined.

  In addition, the expansion / contraction mechanism 160 mentioned above is only an example. For example, the expansion / contraction mechanism 160 is not limited to the two-row structure as shown in FIG. 3, and may be a one-row structure. For example, the expansion / contraction mechanism 160 may have a rhombus structure or a structure using a rhombus in the horizontal direction. The form, number, etc. may be appropriately selected according to the relationship between the suction force and the object to be pulled out.

  As described above, according to the first embodiment, the unit that has been conventionally installed in the machine room can be installed in the radiographing room, so that the space for the machine room can be saved and the MRI apparatus 100 can be installed. Space saving of the entire used space can be realized.

  In particular, in the case of a relatively large unit such as the gradient magnetic field amplifier unit 104 or the RF transmission amplifier unit 107, the effect is great. Moreover, since the gradient magnetic field amplifier unit 104 and the RF transmission amplifier unit 107 use relatively thick cables, these units can be installed on the side of the gantry 110, so that the cable laying distance can be reduced. As a result, signal loss can also be reduced.

  Further, as described above, according to the first embodiment, since it has a safe and simple drawing mechanism, the distance from the side surface of the gantry 110 can be secured without demagnetization, and also in terms of work efficiency. There are also benefits in terms of costs. For example, if it can be pulled out while connected to a power source, adjustments such as LED confirmation and component replacement can be performed in a state close to the actual configuration.

  In addition, since the RF shield case 150 itself is pulled out, the unit can be pulled out by a simple operation without the need to remove or attach the unit itself or remove screws.

(Second Embodiment)
Next, the second embodiment will be described. In the second embodiment, a slide mechanism 170 is proposed as an example of a drawer mechanism. Other points are basically the same as those of the MRI apparatus 100 described in the first embodiment.

  FIG. 4 is a view for explaining a drawing mechanism in the second embodiment. For example, the slide mechanism 170 has two rails as shown in FIGS. 4B and 4C, and the RF shield case 150 with gears slides on the rails. .

  In the second embodiment, this movement is designed to have a certain stiffness against the suction force. For example, as shown in FIG. 5B, the RF shield case 150 may not be easily moved unless a certain amount of force is applied by cutting the rail. In this case, for example, only when the steering wheel is operated, a mechanism in which a certain amount of force is applied and the RF shield case 150 moves by the lever principle may be employed.

  For example, when the RF shield case 150 is pulled out in the pull-out direction and the hand is released from the handle, the RF shield case 150 or a lock mechanism (for example, a lock plate) incorporated in the rail rises and does not move in the suction direction. It may function as a stopper.

  As in the first embodiment, the user may directly carry the RF shield case 150 and pull it out from the magnetic shield case 140, or may use the magnetic shield case 140 or the RF shield case 150. The handle (not shown) attached to the above may be pulled out by hand.

  In addition, the rail of the slide mechanism 170 is folded and shortened step by step so that the rail is housed in the magnetic shield case 140. Alternatively, the rail is installed at a certain height so that the rail is joined to the intermediate joint. Alternatively, the magnetic shield case 140 may be housed in the magnetic shield case 140 by folding it downward.

(Other embodiments)
The embodiment is not limited to the above-described embodiment.

  In the above-described embodiment, the example in which the four units of the gradient magnetic field amplifier unit, the RF transmission amplifier unit, the raw data collection unit, and the image reconstruction unit are installed in the photographing room has been described, but the embodiment is limited to this. It is not a thing. Which unit is installed in the photographing room can be arbitrarily selected. For example, a gradient magnetic field power supply unit or an RF transmission unit may be installed in the imaging room, or a raw data collection unit or an image reconstruction unit may be installed in the machine room. The computer can also be installed in the photographing room, for example, if it is a silicon disk or the like.

  Furthermore, the machine room itself may not be provided, or the machine room may be provided but may be a small space. The same applies to the operation room. That is, the example of the distributed arrangement shown in FIG. 1 is merely an example, and which unit should be installed in which room can be arbitrarily changed according to the environment in which the MRI apparatus is installed. Further, the division of units, the names of units, the names of each part, and the like can be arbitrarily changed.

(cable)
In the above-described embodiment, the state in which the RF shield case 150 is pulled out while the cables of the respective units are connected to the respective units is shown. However, since a relatively thick cable is used for the gradient magnetic field amplifier unit 104 and the RF transmission amplifier unit 107, in this case, an attachment / detachment mechanism that can easily attach / detach the cable may be provided. For example, when pulling out the RF shield case 150 from the magnetic shield case 140, the cable may be disconnected. Alternatively, for example, in the slide mechanism 170 as described in the second embodiment, an energization mechanism such as a metal wiring bus bar may be provided on the rail itself.

(Storage case)
Further, the storage case described in the above-described embodiment is merely an example. For example, you may comprise as one shield case which served as both a magnetic shield case and RF shield case. However, as described above, the RF shield case must have a sealed structure. Therefore, in the case of one shield case serving both as a magnetic shield case and an RF shield case, it is necessary to use a dedicated material used in the magnetic shield case and a sealed structure case.

(Integrated)
In the above-described embodiment, the example in which the magnetic shield case 140 is installed on the side surface of the gantry 110 has been described. However, the embodiment is not limited thereto. The gantry 110 and the magnetic shield case 140 may be integrated. For example, the magnetic shield case 140 itself is accommodated in the cover of the gantry 110, and when the cover (for example, a side cover) of the gantry 110 is removed, the magnetic shield case 140 and the RF shield case 150 installed therein are handled. A structure that can be used may be used.

  According to the magnetic resonance imaging apparatus of at least one embodiment described above, space saving can be realized.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

100 MRI apparatus 140 Magnetic shield case 150 RF shield case

Claims (9)

Equipped with an installation part on which the electronic device can be installed,
A magnetic resonance imaging apparatus comprising: an extraction mechanism that pulls out an electronic device installed in the installation unit to a position away from the gantry by a predetermined distance under excitation of a static magnetic field magnet.   The magnetic resonance imaging apparatus according to claim 1, wherein the predetermined distance is a distance to a position where the attractive force of the magnetic field is reduced to a predetermined value.   The magnetic resonance imaging apparatus according to claim 1, wherein the drawer mechanism pulls out the electronic device by a manual operation.   The said drawing mechanism installs the electronic device in the same position as the position where the electronic device pulled out from the installation unit is installed before the drawer when the electronic device is installed again in the installation unit. The magnetic resonance imaging apparatus according to any one of 1 to 3.   5. The magnetism according to claim 1, wherein the electronic device is installed fixed to the installation unit or the drawer mechanism when installed in the installation unit. 6. Resonance imaging device.   The magnetic resonance imaging apparatus according to claim 1, wherein the installation unit is a shield case that is formed of a material that shields electromagnetic waves and can store the electronic device. The shield case is formed in a double structure of a first shield case that is open on one side and a second shield case that is housed and sealed in the first shield case,
The magnetic resonance imaging apparatus according to claim 6, wherein the drawing mechanism pulls out the electronic device housed in the second shield case together with the second shield case.   The said drawer | drawing-out mechanism has a lock mechanism which restrict | limits with respect to the movement of the said electronic device to the attraction | suction direction of the magnetic field opposite to a drawer | drawing-out direction, The Claim 1 characterized by the above-mentioned. Magnetic resonance imaging device.   The electronic device includes a gradient magnetic field amplifier unit that amplifies a current supplied to a gradient magnetic field coil, an RF transmission amplifier unit that amplifies a current supplied to an RF (Radio Frequency) transmission coil, a raw data collection unit that collects raw data, and The magnetic resonance imaging apparatus according to claim 1, wherein the magnetic resonance imaging apparatus is at least one of image reconstruction units that reconstruct an image from raw data.

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